L6375S

Electrical specifications

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2.8

Over current operation

In order to implement a short circuit protection the output power MOS is driven in linear

connected to the ON DELAY pin according to the following formula:

for

interval with:

When also the Toff interval has expired, the out-put power MOS is switched ON. At this point

in time two conditions may occur

a)

The overloads still present, and then the output power MOS is again driven in

cycle, or

b)

the over load the overload condition is removed, and the output power MOS is no

longer driven in linear mode. All these occurrences are presented on the DIAG2

pin (see fig 2).

We call this unique feature Non Dissipative Short Circuit Protection and it ensures a very

safe operation even in permanent overload conditions. Note that choosing the most

appropriate value for the Ton interval (i.e. the value of the Cdon capacitor) a delay (the Ton

itself) will prevent that a misleading Short Circuit information is presented on the DIAG2

output, when driving capacitive loads (that acts like short circuit in the very beginning)

or Incandescent Lamp (a cold filament has a very low resistive value). The Non Dissipative

Short Circuit Protection can be disabled (keeping Ton = 0 but with the output current still

limited to Isc, and Diagnostic disabled) simply shorting to ground the ON DELAY pin.

Figure 4.

Non dissipative short circuit protection operation